1. Field
Example embodiments relate to a slurry composition for chemical-mechanical polishing (CMP) and a CMP method employing the same, and more particularly, to a slurry composition for chemical-mechanical polishing, having a higher selectivity to SiN, and a CMP method employing the same.
2. Description of the Related Art
In processes of manufacturing a semiconductor device, a chemical mechanical polishing (CMP) method may be widely used to separate a node of a top electrode of a capacitor, as illustrated in FIGS. 1A-1H. Referring to FIG. 1A, a silicon oxide layer 20 may be formed on a semiconductor substrate 10, and a silicon nitride layer 30 may be formed on the silicon oxide layer 20. The silicon nitride layer 30 may act as a CMP stopping layer in the subsequent process.
Referring to FIG. 1B, a trench 40 may be formed using a photolithography method so as to expose a location in which a TiN capacitor may be formed. Referring to FIG. 1C, a TiN layer 50 may be deposited on the exposed surface of the silicon nitride layer 30, the silicon oxide layer 20 and the semiconductor substrate 10. The TiN layer 50 may be formed using a known method, e.g., chemical vapor deposition.
Referring to FIG. 1D, a sacrificial oxide layer 60, acting as a sacrificial layer, may fill the trench 40 and may be formed on the TiN layer 50. As illustrated in FIG. 1E, a portion of the TiN layer 50 removed by CMP may be exposed by performing an etch-back process. Referring to FIG. 1F, an individual TiN node 50a may be formed by performing CMP to separate a TiN node, and the silicon nitride layer 30 may be removed by stripping as illustrated in FIG. 1G. In FIG. 1H, the sacrificial oxide layer 60 and the silicon oxide layer 20 may also be removed by stripping.
In a process of separating a TiN node, when a CMP stopping layer is formed of silicon oxide, a conventional metallic slurry may be sufficient for CMP because the removal rate of the silicon oxide may be relatively low. However, as the design rule is reduced and SiN is used to form a CMP stopping layer, the conventional metallic slurry may not be used because SiN may be more easily removed with the conventional metallic slurry including a ceria (CeO2) polishing agent even when the conventional metallic slurry may have a strong acid condition, e.g., pH of about 3 or less, and even when the solid content of the conventional slurry metallic may be less than about 1 wt. %.